Advance regional control of karst water hazard in floor with ground directional drilling in Chensilou coal mine
In order to further improve the effectiveness of regional treatment technology for karst water damage in mine floor under extremely complex geological structure,reduce the risk of water inrush from floor,and solve the safety technical problems such as karst fissure development,high water pressure,strong water richness,large amount of underground drilling engineering and long construction period in the upper limestone aquifer of Taiyuan Formation in the process of regional water damage treatment in mine,the technology of advanced regional treatment of karst water damage in floor by surface direction-al drilling is put forward through the analysis of the cases and characteristics of water inrush from work-ing face floor after regional treatment in recent years.Based on the mining of 2901 and 2903 test work-ing faces in No.9 mining area of the south wing of the Chensilou coal mine,the L8 limestone aquifer was selected as the target horizon,and the technical parameters of the ground directional hole group were designed.Through the field test,the water pressure of the coal floor and the water absorption rate of each borehole before and after the treatment were analyzed.The results show that the water absorp-tion rate of each borehole decreases obviously after grouting,and the average water absorption rate of boreholes in Z2 and Z3 borehole groups decreases by 97％and 94％respectively;karst fissures are ef-fectively filled after the limestone in the upper section of Taiyuan Formation is reinforced by directional drilling and advanced grouting.After treatment,the water pressure in the L8 limestone of the upper Taiyuan Formation in the area decreases to 1.2～4.2 MPa,and the water pressure distribution is no longer consistent with the buried depth of the stratum,mostly in an isolated island shape;the L8 lime-stone of the upper Taiyuan Formation is transformed into an equivalent aquifuge,and the floor water in-rush coefficient decreases to 0.023～0.057 MPa/m.The successful application of the technology has realized a safe and efficient mining of working face with strong water inrush risk in extremely complex geological structure,and explored a new set of water disaster prevention and control technology for floor karst water disaster in similar fully mechanized mining face of similar mines.
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